The known existing switching mechanism (switching between single and continuous stapling) for a stapler employs an eccentric rod to switch the mode by pressing and spinning it. According to actual practice, however, it is found that the eccentric rod can not be positioned at its desired location well when switching modes between single and continuous stapling, thus under the vibration environment making the stapler lose the capability of switching modes easily. The proposed invention therefore is designed aiming to solve the aforementioned drawbacks.